Influence of Exogenous Gonadotropin and Sexual Steroids on Ovary Development in Japanese Eel Anguilla japonica

外源性促性腺激素與性類固醇對日本鰻卵巢發育影響

王永松(Yung-Song Wang) ； 羅秀婉(Show-Wan Lou)

《臺灣水產學會刊》 34卷3期 (2007/09) Pp. 261-273

https://doi.org/10.29822/JFST.200709.0003

摘要

本研究試驗日本鰻給予外源性性激素刺激下之卵巢發育反應。在短期注射試驗中，以in situ TUNEL方法偵測以鮭魚腦下垂體研磨液與性類固醇（雌二醇及甲基睪固醇）刺激卵黃蓄積初期之卵濾胞，發現在濾胞外層之鞘細胞位置出現細胞程序死亡訊號，並且此訊號所代表之卵細胞初期退化現象與隨後之長期注射試驗中卵細胞數減少有所關聯。在長期注射試驗中，由GSI與總細胞數指出，多次注射雌二醇或甲基睪固醇無法有效地促進日本鰻卵巢之發育。觀察卵徑頻度分佈顯示，雖然在人工誘導性腺成熟過程中，鮭魚腦下垂體研磨液是非常必要之激素，可有效促進日本鰻卵細胞從卵黃蓄積階段發育至卵細胞最後成熟階段。但如果以鮭魚腦下垂體研磨液併用雌二醇，不僅無法有效促進卵巢發育，並且促使卵細胞數顯著減少。雖然甲基睪固醇為一種可被芳香環化酶轉化之雄性素，但從鮭魚腦下垂體研磨液併用甲基睪固醇對促進卵巢發育效果而言，發現此兩種外源性激素在卵黃蓄積過程中同時參與維持卵濾胞的活存與發育同步化。

關鍵字

卵濾胞 ； 人工催熟 ； 性類固醇 ； 退化

並列摘要

This study examines Japanese eel ovary responded to the administration of exogenous sexual hormone throughout the reproductive process. In short-term experiment, ovarian follicle exhibited sensitivity to salmon pituitary homogenate (SPH) and sexual steroids (E2 and MT) in the early vitellogenic stages. The apoptotic signals were exclusively localized in the outer theca layer which was detected from in situ TUNEL, furthermore, the appearance of the apoptotic signal in the early vitellogenic stage seems to correlate with a reduction of oocyte numbers in long-term experiment. In long-term experiment, the mean GSI and total oocyte numbers indicated that multiple injections of E2 or MT were not of much benefit to promote the gonadal development of those fish. Despite SPH treatment was an effective and indispensable method to hasten artificially sexual maturation, and the size-frequency distribution indicated that the most developed oocytes of those were growing from the vitellogenic stage to the final maturational phase. However, the treatment of SPH plus E2 failed to promote the ovarian development and exhibited a remarkable reduction of total oocyte numbers. Of interest is the synergistic effect of SPH plus MT revealed that MT, a potent, aromatizable androgen, provides a potential usefulness to participate the process of vitellogenesis when it combines with SPH treatments, furthermore, the synergistic effect actually enhances the survival and synchronous development of ovarian follicle throughout the reproductive process.

並列關鍵字

Ovarian follicle ； Artificial maturation ； Sexual steroid ； Atresia